The premise of Something Borrowed is classic screwball: A gorgeous romantic, played by 38-year-old Colin Egglesfield, is engaged to party girl Kate Hudson but has unresolved feelings for her meek best friend (Ginnifer Goodwin). And the film's male star, with the smile—big, blinding, knee-buckling—of a puckish young Tom Cruise, marks the return of a bygone breed of leading man. Amid Hollywood's smoldering brooders and nerd-dreamy underdogs, "we forgot that people like Colin exist," says Goodwin, who calls him "Ivy League, 1950s, Kennedy perfection."

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Egglesfield grew up far from Camelot, in a small town outside Chicago, before graduating with a degree in premed biology from the University of Iowa. ("He's a genius!" exclaims Goodwin, who received a crash course in chess from Eggles­field on the evening after their first on-set rehearsal.) But instead of going to med school, a local model search landed him on the Milan runways of Armani, Versace, and Dolce & Gabbana; he also became the face (and body) of Calvin Klein Underwear. "I was at Costco last month when I looked up at a huge crate of Calvin Klein underwear," he says with an embarrassed grin. "There I was, all over the place."

In 2005, Egglesfield landed a pivotal role on All My Children as Susan Lucci's long-lost son, the product of a surreptitious, and soapishly unscientific, "fetus transplant" ("I mean, that's pretty ridiculous," he admits) and later appeared on the CW's short-lived Melrose Place reboot. While he's not the type to enjoy the inevitable downtime of Hollywood life—"There are only so many times you can go to Starbucks in a day," he says—Egglesfield's tightrope act in Borrowed, as a man torn between the comfort of sticking with the wrong woman and the risk of pursuing the right one, leaves us wanting more: Egglesfield recently wrapped another star-studded comedy, BFF & Baby, with Rachel Bilson, Krysten Ritter, and Kate Bosworth.

"Sometimes someone walks into the room and everyone breathes a sigh of relief," Goodwin recalls of Egglesfield's screen test, "because everyone knows this is the person we've been waiting for."